The present invention relates to testing of computer programs. More specifically, the present invention relates to monitoring progress of computer program test design using combinatorial models. A combinatorial model is a set of attributes, values for each attributes, and restrictions on value combinations that may be identified as valid or invalid. A combinatorial model may enable a practitioner to specify tuples, which are combinations of attributes in various test scenarios. In other words, a combinatorial model may span a space of valid tests for testing a computer program to verify that none of the tuples cause undesired behavior when they are encountered during program execution.